By Michael Kanellos
Ascent Solar Technologies (ASTI), which makes copper indium gallium selenide (CIGS) solar cells, says it has boosted the efficiency on its commercial solar cells and modules once again.
Back in November, it's champion solar cell – the best of a manufactured bunch – exhibited around an 11 percent efficiency and the best modules came with a 9.5 percent efficiency, according to Farhad Mogahadam, CEO, in an interview. In March, the company could produce modules on its 1.5 megawatt pilot production line with an efficiency of a little more than 9.5 percent.
Now, the company says that the efficiency on its champion cells has risen to 14 percent and the efficiency for modules have risen to 11.7 percent. The distribution of efficiency on modules runs from 10.5 percent to 11.7 percent, he said. The theoretical maximum for a CIGS solar cell is around 29 percent. the National Renewable Energy Labs has made a cell that can convert nearly 20 percent of the light that strikes it into electricity.
That's a pretty substantial improvement in a short time. It also gives some hope to the CIGS industry. In the past year, skepticism has grown about CIGS: Many manufacturers delayed products and the glut of supply in crystalline silicon has made thin film solar panels less attractive. But higher efficiencies and the lower costs that thin films can provide make thin films still viable.
Ascent employs an evaporation process to deposit the active materials onto a plastic substrate. Evaporation is the oldest and most extensively tested deposition process. (Other deposition processes include sputtering, printing and electroplating.) Most CIGS makers, though, have started out by putting their solar cells on glass. Utilizing plastic cuts material and shipping costs.
The materials are deposited onto the plastic in a chamber at 450 degrees Celsius, but Mogahadam says Ascent can raise the temperature to 550 degrees without harming the substrate.
The Littleton, Colo.-based company's just-inaugurated pilot line can produce 1.5 megawatts of panels per year. Ascent Solar is outfitting a 30-megawatt factory in Thornton, which is north of Denver, and it expects to start production there during the first quarter of 2010.
